Severn Trent, CPL Industries to develop low-carbon solid fuel from food waste

CPL Industries, a UK manufacturer and distributor of smokeless fuels, has partnered with Severn Trent Green Power to transform food waste into low-carbon solid fuels used for heating.

Using hydrothermal carbonisation (HTC) processing, CPL converts the by-product from Severn Trent’s food waste processing to produce low-carbon fuels.

Across its waste sites, Severn Trent processes over 400,000 tonnes of food waste annually. The majority of this is converted into green gas and electricity through the anaerobic digestion (AD) process. The remaining material is recycled to provide a natural fertiliser that is used across the agriculture sector.

Before this fertiliser is spread, it is screened to ensure the best possible quality. The screenings material is a by-product that is hard to break down and sent to energy-from-waste plants.

By processing the by-product at its Immingham plant, CPL can convert this challenging material to produce renewable fuels. Severn Trent is currently trialling its technology further to determine if it can reach 10,000 tonnes of the by-product, which would result in 3,000 tonnes of renewable fuels by CPL.

The HTC manufacturing process for the fuels is low carbon, emitting 15kg of CO₂ per tonne of product produced. The fuels also have low NOx emissions and meet smokeless fuel regulations for Pm2.5 emissions, representing an approximately 80% reduction when compared to coal or untreated wood.

HTC provides a potential solution for digestate leftover from the AD process, which could be a ‘significant issue’ with the government’s planned up-scaling of AD technology to meet its net-zero goals.

HTC fuels can be used in homes to provide heating such as wood burners, as well as in district heating and hard-to-heat sectors such as off-grid businesses in the leisure and hospitality industries.

As a secondary project, Severn Trent and CPL have partnered with the University of Nottingham to establish whether the bio-coal produced from the HTC plant that would be burned as a fuel can be turned into biochar via pyrolysis, fit for sequestration into soil. This would lock a greater proportion of ‘highly-stable’ carbon into the biochar, which can stay stable in the ground for centuries.

The study, which has received funding from the Department for Business, Energy, and Industrial Strategy, will optimise process design and operation for the project to turn up to 30 tonnes of Severn Trent’s food waste AD product into biochar, fit for sequestration. This would provide data that would enable design options to be considered for producing over 600 tonnes of biochar annually – 2,000 tonnes of CO₂ capture equivalent – in the next development phase, to achieve deployment by 2030.